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1. A Comprehensive Map of the Monocyte-Derived Dendritic Cell Transcriptional Network Engaged upon Innate Sensing of HIV

Author

Jarrod S. Johnson, Nicholas De Veaux, Alexander W. Rives, Xavier Lahaye, Sasha Y. Lucas, Brieuc P. Perot, Marine Luka, Victor Garcia-Paredes, Lynn M. Amon, Aaron Watters, Ghaith Abdessalem, Alan Aderem, Nicolas Manel, Dan R. Littman, Richard Bonneau, and Mickaël M. Ménager

Subjects
Biology (General), QH301-705.5
Abstract

Summary: Transcriptional programming of the innate immune response is pivotal for host protection. However, the transcriptional mechanisms that link pathogen sensing with innate activation remain poorly understood. During HIV-1 infection, human dendritic cells (DCs) can detect the virus through an innate sensing pathway, leading to antiviral interferon and DC maturation. Here, we develop an iterative experimental and computational approach to map the HIV-1 innate response circuitry in monocyte-derived DCs (MDDCs). By integrating genome-wide chromatin accessibility with expression kinetics, we infer a gene regulatory network that links 542 transcription factors with 21,862 target genes. We observe that an interferon response is required, yet insufficient, to drive MDDC maturation and identify PRDM1 and RARA as essential regulators of the interferon response and MDDC maturation, respectively. Our work provides a resource for interrogation of regulators of HIV replication and innate immunity, highlighting complexity and cooperativity in the regulatory circuit controlling the response to infection. : Pathogen sensing leads to host transcriptional reprogramming to protect against infection. However, it is unclear how transcription factor activity is coordinated across the genome. Johnson et al. integrate chromatin accessibility and gene expression data to infer and validate a gene regulatory network that directs the innate immune response to HIV. Keywords: network inference, DNA sensing, innate signaling, cGAS, STING, IRF3, NF-κB, chromatin modification, ATAC-seq, RNA-seq

Published
2020
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2. A monocyte/dendritic cell molecular signature of SARS-CoV-2-related multisystem inflammatory syndrome in children with severe myocarditis

Author

Cécile Masson, Aurélien Corneau, Florence Moulin, Ghaith Abdessalem, Pedro Gonçalves, Marianne Leruez, James P. Di Santo, Mathie Lorrot, Julie Toubiana, Julien Haroche, Camille Bruneau, Isabelle Melki, Bruno Charbit, Zahra Belhadjer, Loïc de Pontual, Camille de Cevins, Brigitte Bader Meunier, Alain Fischer, Victor Garcia-Paredes, Brieuc P. Perot, Marine Luka, Damien Bonnet, Quentin Riller, Nikaïa Smith, Slimane Allali, Sonia Meynier, Aude Magérus, Christele Gras Leguen, Shen-Ying Zhang, Olivier Schwartz, Jean-Laurent Casanova, Frédéric Rieux-Laucat, Nicolas Cagnard, Francesco Carbone, Tinhinane Fali, Mélanie Parisot, Mickaël M. Ménager, Maxime Beretta, Mohammed Zarhrate, Christine Bole-Feysot, Vithura Pirabarakan, Ludivine Grzelak, Mehdi Oualha, Darragh Duffy, Laura Barnabei, Hugo Mouquet, Maxime Batignes, Alexandre Boullé, Boris Sorin, Marie-Claude Stolzenberg, Inflammatory Responses and Transcriptomic Networks in diseases (Equipe Inserm U1163), Imagine - Institut des maladies génétiques (IHU) (Imagine - U1163), Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Paris Cité (UPCité)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Paris Cité (UPCité), Sanofi Aventis R&D [Chilly-Mazarin], Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Paris Cité (UPCité), Immunologie Translationnelle - Translational Immunology lab, Institut Pasteur [Paris] (IP), Immunogenetics of pediatric autoimmune diseases (Equipe Inserm U1163), Cytometrie et Biomarqueurs – Cytometry and Biomarkers (UTechS CB), Immunologie humorale - Humoral Immunology, Institut Pasteur [Paris] (IP)-Institut National de la Santé et de la Recherche Médicale (INSERM), Virus et Immunité - Virus and immunity (CNRS-UMR3569), Institut Pasteur [Paris] (IP)-Centre National de la Recherche Scientifique (CNRS), Immunité Innée - Innate Immunity, Structure Fédérative de Recherche Necker (SFR Necker - UMS 3633 / US24), Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Cytométrie Pitié-Salpêtrière (PASS-CYPS), Unité Mixte de Service Production et Analyse de données en Sciences de la vie et en Santé (PASS), Institut National de la Santé et de la Recherche Médicale (INSERM)-Sorbonne Université (SU)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Sorbonne Université (SU), Human genetics of infectious diseases : Mendelian predisposition (Equipe Inserm U1163), Rockefeller University [New York], CHU Necker - Enfants Malades [AP-HP], Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP), Centre d'Immunologie et des Maladies Infectieuses (CIMI), Institut National de la Santé et de la Recherche Médicale (INSERM)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), CHU Pitié-Salpêtrière [AP-HP], Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Sorbonne Université (SU), AP-HP Hôpital universitaire Robert-Debré [Paris], Université Paris Cité (UPCité), CHU Trousseau [APHP], Centre d’Investigation Clinique de Nantes (CIC Nantes), Université de Nantes (UN)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre hospitalier universitaire de Nantes (CHU Nantes), Hôpital Jean Verdier [AP-HP], Université Paris 13 (UP13), Collège de France (CdF (institution)), Biodiversité et Epidémiologie des Bactéries pathogènes - Biodiversity and Epidemiology of Bacterial Pathogens, ANR-18-IDEX-0001,Université de Paris,Université de Paris(2018), ANR-17-EURE-0013,GENE,Génétique et Epigénétique Nouvelle Ecole(2017), ANR-18-RHUS-0010,ATRACTION,Autoimmunity/inflammation Through Rnaseq Analysis at the single Cell level for Therapeutic Innovation(2018), Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Paris Cité (UPC)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Paris Cité (UPC), Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Paris Cité (UPC), Institut Pasteur [Paris], Institut Pasteur [Paris]-Institut National de la Santé et de la Recherche Médicale (INSERM), Virus et Immunité - Virus and immunity, Institut Pasteur [Paris]-Centre National de la Recherche Scientifique (CNRS), Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPC), and Université Paris Cité (UPC)

Subjects
Adult, Vascular Endothelial Growth Factor A, Chemokine, Myocarditis, medicine.medical_treatment, [SDV]Life Sciences [q-bio], MIS-C, Monocytes, chemistry.chemical_compound, Viewpoint, scRNA-seq, medicine, otorhinolaryngologic diseases, Humans, Kawasaki Disease, Child, Connective Tissue Diseases, biology, business.industry, SARS-CoV-2, Monocyte, NF-kappa B, COVID-19, General Medicine, Dendritic Cells, Gene signature, medicine.disease, Pathophysiology, Systemic Inflammatory Response Syndrome, Vascular endothelial growth factor, medicine.anatomical_structure, Cytokine, chemistry, TNF-α and NF-κB signaling, Immunology, biology.protein, Cytokines, Tumor necrosis factor alpha, lack of responses to type I and type II IFN secretion, Clinical and Translational Article, Chemokines, myocarditis, business, PIMS-TS
Abstract

Background Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in children is generally milder than in adults, but a proportion of cases result in hyperinflammatory conditions often including myocarditis. Methods To better understand these cases, we applied a multiparametric approach to the study of blood cells of 56 children hospitalized with suspicion of SARS-CoV-2 infection. Plasma cytokine and chemokine levels and blood cellular composition were measured, alongside gene expression at the bulk and single-cell levels. Findings The most severe forms of multisystem inflammatory syndrome in children (MIS-C) related to SARS-CoV-2 that resulted in myocarditis were characterized by elevated levels of pro-angiogenesis cytokines and several chemokines. Single-cell transcriptomics analyses identified a unique monocyte/dendritic cell gene signature that correlated with the occurrence of severe myocarditis characterized by sustained nuclear factor κB (NF-κB) activity and tumor necrosis factor alpha (TNF-α) signaling and associated with decreased gene expression of NF-κB inhibitors. We also found a weak response to type I and type II interferons, hyperinflammation, and response to oxidative stress related to increased HIF-1α and Vascular endothelial growth factor (VEGF) signaling. Conclusions These results provide potential for a better understanding of disease pathophysiology. Funding Agence National de la Recherche (Institut Hospitalo-Universitaire Imagine, grant ANR-10-IAHU-01; Recherche Hospitalo-Universitaire, grant ANR-18-RHUS-0010; Laboratoire d’Excellence ‘‘Milieu Intérieur,” grant ANR-10-LABX-69-01; ANR-flash Covid19 “AIROCovid” and “CoVarImm”), Institut National de la Santé et de la Recherche Médicale (INSERM), and the “URGENCE COVID-19” fundraising campaign of Institut Pasteur., Graphical abstract, Context and significance Children with SARS-CoV-2 infection were initially thought to have only mild COVID-19 symptoms. However, several weeks into the first wave of SARS-CoV-2 infections, there was a surge of a postacute pathology called multisystem inflammatory syndrome in children (MIS-C). The authors recruited a cohort of children with suspicion of SARS-CoV-2 infection and uncovered hyperinflammation, hypoxic conditions, exacerbation of TNF-α signaling via NF-κB, and absence of responses to type I and type II IFN secretion in the most severe forms of MIS-C with severe myocarditis. This work led the authors to identify in monocytes and validate in peripheral blood mononuclear cells a molecular signature of 25 genes that allows discrimination of the most severe forms of MIS-C with myocarditis., Multiparametric analysis identifies, in monocytes and dendritic cells, a molecular signature of the most severe forms of multisystem inflammatory syndrome in children caused by SARS-CoV-2 infection. Severe myocarditis is characterized by an excess of TNF-α signaling via NF-κB, hypoxic conditions, and hyperinflammation in the absence of type I and type II interferon responses.

Published
2021
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3. A Comprehensive Map of the Monocyte-Derived Dendritic Cell Transcriptional Network Engaged upon Innate Sensing of HIV

Author

Nicholas De Veaux, Victor Garcia-Paredes, Mickaël M. Ménager, Xavier Lahaye, Lynn M. Amon, Jarrod S. Johnson, Alexander W. Rives, Marine Luka, Dan R. Littman, Nicolas Manel, Richard Bonneau, Brieuc P. Perot, Alan Aderem, Sasha Y. Lucas, Aaron Watters, Ghaith Abdessalem, Immunité et cancer (U932), and Université Paris Descartes - Paris 5 (UPD5)-Institut Curie [Paris]-Institut National de la Santé et de la Recherche Médicale (INSERM)

Subjects
Male, 0301 basic medicine, [SDV]Life Sciences [q-bio], HIV Infections, ATAC-seq, Biology, Article, Monocytes, General Biochemistry, Genetics and Molecular Biology, 03 medical and health sciences, chemistry.chemical_compound, 0302 clinical medicine, Interferon, medicine, Humans, Gene Regulatory Networks, Promoter Regions, Genetic, Transcription factor, lcsh:QH301-705.5, Innate immune system, Retinoic Acid Receptor alpha, Cell Differentiation, NF-κB, Dendritic Cells, Dendritic cell, Chromatin, Immunity, Innate, 3. Good health, Cell biology, HEK293 Cells, 030104 developmental biology, Gene Expression Regulation, chemistry, lcsh:Biology (General), Interferon Type I, HIV-1, Female, Transcriptome, IRF3, 030217 neurology & neurosurgery, Transcription Factors, medicine.drug
Abstract

SUMMARY Transcriptional programming of the innate immune response is pivotal for host protection. However, the transcriptional mechanisms that link pathogen sensing with innate activation remain poorly under-stood. During HIV-1 infection, human dendritic cells (DCs) can detect the virus through an innate sensing pathway, leading to antiviral interferon and DC maturation. Here, we develop an iterative experimental and computational approach to map the HIV-1 innate response circuitry in monocyte-derived DCs (MDDCs). By integrating genome-wide chromatin accessibility with expression kinetics, we infer a gene regulatory network that links 542 transcription factors with 21,862 target genes. We observe that an interferon response is required, yet insufficient, to drive MDDC maturation and identify PRDM1 and RARA as essential regulators of the interferon response and MDDC maturation, respectively. Our work provides a resource for interrogation of regulators of HIV replication and innate immunity, highlighting complexity and cooperativity in the regulatory circuit controlling the response to infection., Graphical Abstract, In Brief Pathogen sensing leads to host transcriptional reprogramming to protect against infection. However, it is unclear how transcription factor activity is coordinated across the genome. Johnson et al. integrate chromatin accessibility and gene expression data to infer and validate a gene regulatory network that directs the innate immune response to HIV.

Published
2020
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4. A monocyte/dendritic cell molecular signature of SARS-CoV2-related multisystem inflammatory syndrome in children (MIS-C) with severe myocarditis

Author

Ludivine Grzelak, Maxime Beretta, Slimane Allali, Aude Magérus, Hugo Mouquet, Maxime Batignes, Isabelle Melki, Olivier Schwartz, Quentin Riller, Mehdi Oualha, Nicolas Cagnard, Christine Bole-Feysot, Camille de Cevins, James P. Di Santo, Christele Gras Leguen, Florence Moulin, Jean-Laurent Casanova, Cécile Masson, Aurélien Corneau, Damien Bonnet, Vithura Pirabarakan, Mickaël M. Ménager, Camille Bruneau, Brieuc P. Perot, Francesco Carbone, Darragh Duffy, Mohammed Zarhrate, Marie-Claude Stolzenberg, Alexandre Boullé, Mélanie Parisot, Boris Sorin, Ghaith Abdessalem, Alain Fischer, Marianne Leruez, Julie Toubiana, Victor Garcia-Paredes, Mathie Lorrot, Loïc de Pontual, Zahra Belhadjer, Bruno Charbit, Tinhinane Fali, Marine Luka, Nikaïa Smith, Brigitte Bader Meunier, Shen-Ying Zhang, Sonia Meynier, Fredéric Rieux Laucat, Julien Haroche, Pedro Gonçalves, Laura Barnabei, Inflammatory Responses and Transcriptomic Networks in diseases (Equipe Inserm U1163), Imagine - Institut des maladies génétiques (IHU) (Imagine - U1163), Institut National de la Santé et de la Recherche Médicale (INSERM)-Université de Paris (UP)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université de Paris (UP), Sanofi Aventis R&D [Chilly-Mazarin], Immunologie Translationnelle - Translational Immunology lab, Institut Pasteur [Paris], Immunogenetics of pediatric autoimmune diseases (Equipe Inserm U1163), Cytometrie et Biomarqueurs – Cytometry and Biomarkers (UTechS CB), Immunologie humorale - Humoral Immunology, Institut Pasteur [Paris]-Institut National de la Santé et de la Recherche Médicale (INSERM), Virus et Immunité - Virus and immunity, Institut Pasteur [Paris]-Centre National de la Recherche Scientifique (CNRS), Immunité Innée - Innate Immunity, Institut National de la Santé et de la Recherche Médicale (INSERM)-Université de Paris (UP), Structure Fédérative de Recherche Necker (SFR Necker - UMS 3633 / US24), Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Cytométrie Pitié-Salpêtrière (PASS-CYPS), Unité Mixte de Service Production et Analyse de données en Sciences de la vie et en Santé (PASS), Sorbonne Université (SU)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Sorbonne Université (SU)-Institut National de la Santé et de la Recherche Médicale (INSERM), Human genetics of infectious diseases : Mendelian predisposition (Equipe Inserm U1163), Rockefeller University [New York], Service d'immuno-hématologie pédiatrique [CHU Necker], Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-CHU Necker - Enfants Malades [AP-HP], Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP), Service d'Immunologie [CHU Pitié-Salpétrière], CHU Pitié-Salpêtrière [AP-HP], Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Sorbonne Université (SU)-Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Sorbonne Université (SU), AP-HP Hôpital universitaire Robert-Debré [Paris], CHU Trousseau [APHP], Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Sorbonne Université (SU), Département des urgences pédiatriques [CHU Necker], CHU Necker - Enfants Malades [AP-HP], Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP), Laboratoire de Virologie [CHU Necker], Département de Pédiatrie et maladies infectieuses [CHU Necker], Centre hospitalier universitaire de Nantes (CHU Nantes), Service de Pédiatrie [Jean Verdier], Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Hôpital Jean Verdier [AP-HP], Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Université Sorbonne Paris Nord, Collège de France (CdF (institution)), Biodiversité et Epidémiologie des Bactéries pathogènes - Biodiversity and Epidemiology of Bacterial Pathogens, The study was supported by the Institut National de la Santé et de la Recherche Médicale (INSERM), by the 'URGENCE COVID-19' fundraising campaign of Institut Pasteur, by the Atip-Avenir, Emergence ville de Paris program and fond de dotation Janssen Horizon and by government grants managed by the Agence National de la Recherche as part of the 'Investment for the Future' program (Institut Hospitalo-Universitaire Imagine, grant ANR-10-IAHU-01, Recherche Hospitalo-Universitaire, grant ANR-18-RHUS-0010, Laboratoire d’Excellence ‘‘Milieu Intérieur', grant ANR-10-LABX-69-01), the Centre de Référence Déficits Immunitaires Héréditaires (CEREDIH), the Agence National de la Recherche (ANR-flash Covid19 'AIROCovid' to FRL and 'CoVarImm' to DD and JDS), and by the FAST Foundation (French Friends of Sheba Tel Hashomer Hospital). The LabTech Single Cell@Imagine is supported by the Paris Region and the 'Investissements d’avenir' program through the 2019 ATF funding – Sésame Filières PIA (Grant N°3877871). CdC is the recipient of a CIFRE-PhD (Sanofi). L.B. was a recipient of an Imagine institute PhD international program supported by the Fondation Bettencourt Schueller. L.B. was also supported by the EUR G.E.N.E. (reference #ANR-17-EURE-0013) and is part of the Université de Paris IdEx #ANR-18-IDEX-0001 funded by the French Government through its 'Investments for the Future' program. S.M. was a recipient of an INSERM and Institut Imagine post-doctorat program supported by the Fondation pour la Recherche Médicale (FRM N°SPF20170938825). NS was a recipient of the Pasteur-Roux-Cantarini Fellowship. VGP obtained an Imagine international PhD fellowship program supported by the Fondation Bettencourt Schueller. BPP is the recipient of an ANRS post-doctoral fellowship., ANR-10-IAHU-0001,Imagine,Institut Hospitalo-Universitaire Imagine(2010), ANR-18-RHUS-0010,ATRACTION,Autoimmunity/inflammation Through Rnaseq Analysis at the single Cell level for Therapeutic Innovation(2018), ANR-10-LABX-0069,MILIEU INTERIEUR,GENETIC & ENVIRONMENTAL CONTROL OF IMMUNE PHENOTYPE VARIANCE: ESTABLISHING A PATH TOWARDS PERSONALIZED MEDICINE(2010), ANR-20-COVI-0022,AIROCovid19,Analyse Omics de la réponse immune aigue au cours de l'infection à Covid19: rationnel moléculaire pour un traitement ciblé(2020), ANR-17-EURE-0013,GENE,Génétique et Epigénétique Nouvelle Ecole(2017), ANR-18-IDEX-0001,Université de Paris,Université de Paris(2018), Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Paris Cité (UPCité)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Paris Cité (UPCité), Institut Pasteur [Paris] (IP), Institut Pasteur [Paris] (IP)-Institut National de la Santé et de la Recherche Médicale (INSERM), Virus et Immunité - Virus and immunity (CNRS-UMR3569), Institut Pasteur [Paris] (IP)-Centre National de la Recherche Scientifique (CNRS), Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Paris Cité (UPCité), Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), and Institut National de la Santé et de la Recherche Médicale (INSERM)-Sorbonne Université (SU)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Sorbonne Université (SU)

Subjects
0303 health sciences, Chemokine, Myocarditis, biology, business.industry, Monocyte, Dendritic cell, Gene signature, medicine.disease_cause, medicine.disease, Pathophysiology, 3. Good health, 03 medical and health sciences, 0302 clinical medicine, medicine.anatomical_structure, 030220 oncology & carcinogenesis, Immunology, biology.protein, medicine, [SDV.IMM]Life Sciences [q-bio]/Immunology, Tumor necrosis factor alpha, business, Oxidative stress, 030304 developmental biology
Abstract

SARS-CoV-2 infection in children is generally milder than in adults, yet a proportion of cases result in hyperinflammatory conditions often including myocarditis. To better understand these cases, we applied a multi-parametric approach to the study of blood cells of 56 children hospitalized with suspicion of SARS-CoV-2 infection. The most severe forms of MIS-C (multisystem inflammatory syndrome in children related to SARS-CoV-2), that resulted in myocarditis, were characterized by elevated levels of pro-angiogenesis cytokines and several chemokines. Single-cell transcriptomic analyses identified a unique monocyte/dendritic cell gene signature that correlated with the occurrence of severe myocarditis, characterized by sustained NF-κB activity, TNF-α signaling, associated with decreased gene expression of NF-κB inhibitors. We also found a weak response to type-I and type-II interferons, hyperinflammation and response to oxidative stress related to increased HIF-1α and VEGF signaling. These results provide potential for a better understanding of disease pathophysiology.

Published
2021

5. Dendritic Cell Maturation Regulates TSPAN7 Function in HIV-1 Transfer to CD4+ T Lymphocytes

Author

Brieuc P. Perot, Victor García-Paredes, Marine Luka, and Mickaël M. Ménager

Subjects
HIV-1, trans-infection, TSPAN7, actin nucleation, dendritic cell maturation, kinetic of transfer, Microbiology, QR1-502
Abstract

Dendritic cells (DCs) serve a key function in host defense, linking innate detection of microbes to activation of pathogen-specific adaptive immune responses. DCs express cell surface receptors for HIV-1 entry, but are relatively resistant to productive viral replication. They do, however, facilitate infection of co-cultured T-helper cells through a process referred to as trans-infection. We previously showed that tetraspanin 7 (TSPAN7), a transmembrane protein, is involved, through positive regulation of actin nucleation, in the transfer of HIV-1 from the dendrites of immature monocyte-derived DCs (iMDDCs) to activated CD4+ T lymphocytes. Various molecular mechanisms have been described regarding HIV-1 trans-infection and seem to depend on DC maturation status. We sought to investigate the crosstalk between DC maturation status, TSPAN7 expression and trans-infection. We followed trans-infection through co-culture of iMDDCs with CD4+ T lymphocytes, in the presence of CXCR4-tropic replicative-competent HIV-1 expressing GFP. T cell infection, DC maturation status and dendrite morphogenesis were assessed through time both by flow cytometry and confocal microscopy. Our previously described TSPAN7/actin nucleation-dependent mechanism of HIV-1 transfer appeared to be mostly observed during the first 20 h of co-culture experiments and to be independent of HIV replication. In the course of co-culture experiments, we observed a progressive maturation of MDDCs, correlated with a decrease in TSPAN7 expression, a drastic loss of dendrites and a change in the shape of DCs. A TSPAN7 and actin nucleation-independent mechanism of trans-infection, relying on HIV-1 replication, was then at play. We discovered that TSPAN7 expression is downregulated in response to different innate immune stimuli driving DC maturation, explaining the requirement for a TSPAN7/actin nucleation-independent mechanism of HIV transfer from mature MDDCs (mMDDCs) to T lymphocytes. As previously described, this mechanism relies on the capture of HIV-1 by the I-type lectin CD169/Siglec-1 on mMDDCs and the formation of a “big invaginated pocket” at the surface of DCs, both events being tightly regulated by DC maturation. Interestingly, in iMDDCs, although CD169/Siglec-1 can capture HIV-1, this capture does not lead to HIV-1 transfer to T lymphocytes.

Published
2020
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